Arrangement for safety belt

ABSTRACT

A safety belt arrangement for protecting passengers in motor driven vehicles comprises a strap roller having a spindle mounted for rotation in a housing, a belt strap wound on the spindle, biasing means for urging the belt strap to wind on the spindle, a locking mechanism to lock the spindle against unwinding rotation, a detector for sensing a reference surface or surfaces on the spindle or on the belt strap and a memory device to register the time interval between signals received from the detector to determine the unwinding velocity of the belt strap and to activate the locking mechanism when a preselected value of the unwinding velocity of the belt strap is exceeded.

The present invention relates to safety belts for passengers in vehiclessuch as motor cars, aeroplanes and other wheeled vehicles etc. Moreclosely defined, the invention relates to such safety belts as compriseat least one strap roller for winding on and off at least one belt strapas well as at least one locking arrangement which locks the belt strapand prevents further unwinding from the strap roller once a limit valuehas been exceeded as regards the belt strap speed/acceleration and theacceleration/deceleration/inclination of the vehicle, aeroplane etc. oras regards any other condition such as speed/height etc. at which thebelt strap must be locked.

All previously known designs have the disadvantage that they are notequipped quickly and accurately to sense and prevent unwinding from thestrap roller once a limit value in respect of a certain condition hasbeen exceeded or reached.

The present invention aims at overcoming the above and otherdisadvantages of known safety belt systems. This was achieved as soon asthe arrangement for a safety belt herewith described and explainedbelow, from which it follows that one main feature of the inventionconsists in that the belt strap is locked against unwinding with the aidof at least one locking arrangement which is activated when apreselected limit value has been reached or exceeded as regards thespeed/acceleration of the belt strap or theacceleration/deceleration/inclination of the vehicle etc.

The invention is described in detail below with reference to theattached drawings and diagrammatic presentations in which

FIG. 1 is a diagrammatic view showing an embodiment of a safety beltarrangement in which a reference surface/surfaces arranged on a strapspindle in accordance with the invention is/are sensed.

FIG. 2 is a diagrammatic view showing an embodiment of a safety beltarrangement in which a reference surface/surfaces arranged on the beltstrap in accordance with the invention is/are sensed.

FIG. 2' is a perspective view of the safety belt shown in FIG. 2.

FIG. 3a is an end view of the strap spindle in accordance with theinvention.

FIG. 3b is a side view of the strap spindle shown in FIG. 3a.

FIG. 3c is a view showing the opposite end of the strap spindle of FIG.3a.

FIG. 4a is an end view of the lock casing in accordance with theinvention.

FIG. 4b is a side view of the lock casing shown in FIG. 4a.

FIG. 5 is a block diagram illustrating in general terms a strap speeddetector in accordance with the invention.

FIG. 6 is a block diagram illustrating a strap speed detector withoptical sensing in accordance with the invention.

FIG. 7 is a diagrammatic view of anacceleration/deceleration/inclination detector for vehicles, aeroplanesetc. in accordance with the invention.

FIG. 8 is a block diagram of an acceleration/deceleration/inclinationdetector in accordance with the invention.

FIG. 9 is a block diagram of a belt take-up detector in accordance withthe invention.

FIG. 1 shows a safety belt system comprising (at least) one belt strap(1) which can be wound on to/unwound from a spindle (2) mounted withinan appropriately formed frame housing (3), which is secured at therequired point in the vehicle. A winding device (4), e.g. a helicalspring, is linked with the shaft (2) and arranged to maintain the beltstrap (1) wound on to the spindle (2). The free end of the strap isprovided with some suitable locking mechanism, e.g. a diagrammaticallyillustrated male part (5) which can be locked by insertion into acorresponding female part (6), also shown in diagrammatic form andlocated at a required suitable point in the vehicle. The above parts maybe of as such well known design. Strap spindle (2) is provided with atleast one reference surface (10), as shown in FIG. 3, which is sensed bya detector (7) arranged in a casing (9) stationary relative to the straproller.

The reference surface/surfaces (10) can be conductive, surrounded bynon-conductive layers and sensed by an appropriate detector such aspickup brushes. The reference surface/surfaces can be reflective,surrounded by non-reflective layers and sensed by an optical detector,or magnetic, surrounded by non-magnetic layers and sensed by anappropriate detector (inductive sensing). These are only examples of areference surface/surfaces with an appropriately adapted sensingdetector.

FIGS. 2 and 2' differ from FIG. 1 to the extent that the referencesurface/surfaces (10) is/are arranged on belt strap (1) and the detector(7) is arranged within a casing (22) stationary relative to the straproller and situated within the sensor casing (9"). As for the referencesurface/surfaces, this is/these are reflective, magnetic or of similartype with an appropriate sensing detector. Some examples are describedabove in connection with FIG. 1.

FIG. 3 shows an embodiment of the strap spindle (2) with sensingsurfaces (10) arranged on its side (2a).

FIG. 4 shows an embodiment of a lock casing (9) arranged for receiving asensing detector within a corresponding casing (9').

FIG. 5 shows in general terms how the reference surface/surfaces is/aresensed by a detector. Pulses from the sensing detector (7) aretransmitted via a pulse forming circuit to the strap speed detectorunit. Two consecutive pulses are fed into two memory circuits "N" and"N-1" whereby a time circuit measures the interval between the pulses.The time circuit has a constant (but variable number) corresponding tothe limit value for the strap speed/acceleration. If this value isexceeded the time circuit passes a signal to a locking arrangement (8)whereby the belt strap is prevented from unwinding. The lockingarrangement can be an electric magnet, a motor or a similar device.

FIG. 6 shows an embodiment with a reference surface/surfaces suitablefor optical sensing. In all other respects it is identical with FIG. 3.

FIG. 7 shows the other detector, i.e. theacceleration/deceleration/inclination detector (12a). The latterconsists of a substantially cup-shaped and conical support (14) andcomprises a sphere (15) displaceable in every radial direction from aposition of rest at the lowest point (16). With the detector (7) a lightemitter (17) is preferably located in the opening (18) of the cover ofthe cup, which coincides with a light receiver (19), in this case on theunderside of the cup. The cup consists of transparent material such asglass, transparent plastic or a similar substance. The light receiver(19) is connected to a pulse-forming circuit and when the sphere movesfrom the centre as a result of acceleration/deceleration/inclination asignal is given, whenever the light (20) from the light emitter (17) issensed by the light receiver (19).

FIG. 8 shows a block diagram relating to theacceleration/deceleration/inclination detector. Further to thedescription of the above detector (12a) (FIG. 7) it operates in that thelight receiver's signal (which occurs when the sphere moves from thecentre and passes through light (20) from the light emitter) is pulsedso as to activate via an activating circuit at least one lockingarrangement (8) through control unit (11). The inclination value dependson the angle of conicity (β) of the cup. The light emitter may be aninfra-red light emitter with a corresponding suitable light receiver.Furthermore, the cup-shaped conical support (14) may be filled withliquid in order to achieve a required degree of inertia (so that thesphere will not move at relatively low acceleration/decelerationvalues). Since the sphere moves in every radial directionacceleration/deceleration/inclination can be sensed irrespective of thedirection throughout 360°.

The electronic/electrical control/regulating unit and the arrangementshown in the drawings operate as follows: The control/regulating unit(11) is connected to a suitable current source such as a car battery,advantageously via a fuse and an accumulator with adequate capacity toenable at least one belt locking operation after possible failure orshort-circuiting of the current source.

If the control unit (11) also comprises a belt take-up control system,the actual number of passengers is set at the control unit (11). Thepassengers put on the belts. If the arrangement is used in conjunctionwith arrangements for controlling belt fastening at the lock the controlunit (11) can be so designed that locking of the strap winding mechanismis only possible if the lock components are correctly inserted in oneanother (see FIG. 9).

FIG. 1 shows a strap speed/acceleration detector (7) which transmits asignal to a locking arrangement (8) when the said preselected value isexceeded. The detector (7) may be designed in various ways and may, forexample, be a transducer rotating together with strap spindle (2). Withthis embodiment (FIG. 6) the detector (7) is an opto-electric detectorlocated on the sensor casing (9') outside the rotary spindle (2). Thedetector cooperates with one or several reflective surfaces (10) locatedcentrally opposite the detector (7) rotating jointly with the strapspindle (2).

Since the reference surface/surfaces (10) is/are fixed the time intervalbetween the detection of two consecutive reference surfaces constitutesa measure for the strap unwinding speed/acceleration. By comparison withan appropriate time circuit (described below) the unwindingspeed/acceleration can be simply read and when it exceeds thepreselected limit value a locking arrangement (8) is activated, whichlocks the strap spindle (2) in relation to the frame. The detector (7)may also be designed in other ways (FIG. 5) (see description in respectof FIG. 1).

FIGS. 2 and 2' differ from FIG. 1 inasmuch as the reference surfaces arearranged on the belt strap. The belt strap passes through an opening(21) centrally opposite one side of which (22) there is a sensor casing(9") which houses a detector (7). The belt strap must be provided withseveral reference surfaces separated to a certain extent on that part ofthe strap which is wound on to or unwound from the strap roller. Sincethe reference surfaces are fixed the time interval between the detectionof two consecutive reference surfaces is a measure of the strapunwinding speed/acceleration. By comparison with a suitable time circuit(described below) the strap unwinding speed/acceleration can be simplyread and when it exceeds or reaches the preselected limit value at leastone locking arrangement (8) is activated, which locks the belt strapthus preventing it from unwinding.

In e.g. a car it is sufficient to install a sensing detector in thedriver's strap roller whereby, once the preselected value of strapspeed/acceleration has been reached, all locking arrangements in theremaining strap rollers not provided with sensing detectors areactivated. Similarly it is the case that not more than oneacceleration/deceleration/inclination detector is required in a car.

Triggering of at least one locking arrangement (8) by the detector (7)is preferably effected by means of an electrical/electronic control unit(11) described in detail below. The strap locking mechanism differs fromthe existing types in that locking of the belt strap so as to preventunwinding is brought about with the aid of at least oneelectrical/electronic arrangement which passes a pulse to at least onelocking arrangement (8) as soon as a preselected strapspeed/acceleration value has been reached or exceeded. With this designan accurate and speedy reading of the strap speed/acceleration isachieved, a signal being transmitted to a locking arrangement (8), whichlocks the belt strap quickly and reliably so as to prevent unwinding.With the aid of the strap speed/acceleration detector a change in stateas regards the speed/acceleration of the strap is measured whereby atleast one locking arrangement is activated so as to lock the belt strapand prevent it from unwinding once the preselected beltspeed/acceleration limit value has been measured.

Similarly the control unit (11) may register when the preselectedacceleration/deceleration/inclination occurs. In this case the controlunit (11) is connected with the strap speed/acceleration detector (7),the acceleration/deceleration/inclination detector (12a) and a belttake-up detector (12b) and may possibly be connected with aspeed/altitude detector (12c) and also a stillstand detector (12d).

All detectors connected with the control unit (11) have this in commonthat they coordinate and activate at least one locking arrangement (8)when a certain limit value for a detector has been reached or exceededwhereby at least one belt strap is locked so as to prevent it fromunwinding. Going beyond the above examples the control unit (11) maye.g. be connected to the strap lock in a simple manner. For instance asuitably located contact or microswitch may indicate when the lockingelement is in the locking position whereby a corresponding signal ispassed to the control unit (11). The system can be supplemented andrefined by providing a speed/height detector (12c) in vehicles,aeroplanes etc. so that when a certain speed/height is measured inrespect of them a signal is passed to the control unit (11) and to astillstand detector (12d) which senses when the vehicle is stationary.

The electrical/electronic control unit (11) may e.g. comprise even morestate detectors. The most essential are the strap speed/accelerationdetector and the acceleration/deceleration/inclination detector as wellas (12b) and possibly (12c). The electrical/electronic control unit mayalso comprise a belt take-up detector (FIG. 9). The belt take-updetector makes it possible to ensure correct insertion of the malelocking component into the female locking component. When the beltlocking components are inserted a signal is passed from every such lockto the control unit (11), whereby locking arrangements are operated assoon as the limit values of various detectors have been reached orexceeded. With incorrect locking of the belt locking components or ifthe belt is not put on a warning signal is given until the belt has beenput on. With such a belt take-up detector the locking arrangement/s canbe operated only after the passenger/s have put on the belt so that themale locking component is correctly inserted in the female lockingcomponent.

In block diagram (FIG. 9) a passenger sensing circuit senses when thepassenger sits down on his seat. A signal is passed to the control unitas a result of which the belt components are locked provided that thelocking arrangement/s is/are released within a preselected time, e.g. 30seconds. This enables the passenger to put on the belt without repeatedlocking of the strap roller. Once the preselected time has elapsed awarning signal is given through an output unit such as a buzzer, analarm light or a similar device until the belt has been put on. If thebelt has been put on the contact for the locking arrangement/s closes.Closing of the contact causes these locking arrangements to operate andto be activated whenever the state detectors sense that a limit valuehas been reached or exceeded.

With reference to FIG. 9, the belt take-up detector differs fromexisting types in that it is equipped with a time circuit with apreselected (but variable) number so that when the number is exceeded analarm signal is released through an output unit of a warning circuit. Inaddition, the said belt take-up detector makes it possible to increasethe passengers' comfort by not producing a warning signal as soon as apassenger has sat down on his seat but also inasmuch as the lockingarrangement/s can be activated only if the belt has been put oncorrectly and not while one is putting on the belt strap in order tolock it.

The invention is of course not limited to the above embodimentsspecially shown in the drawings, many modifications and variations beingpossible within the framework of the following patent claims.

I claim:
 1. A safety belt arrangement for protecting passengers in motordriven vehicles, comprising:at least one strap roller having a spindlemounted for rotation in a housing attached to the vehicle body; at leastone belt strap, one free end of which is attached to said spindle andwhich can be wound onto and unwound from said spindle; biasing meansurging said spindle to rotate so as to keep said belt strap wound ontosaid spindle; locking means actuable for locking said spindle so as toprevent further unwinding of said belt strap; at least one referencesurface provided on said rotating spindle; a detector which on unwindingof said belt strap senses said at least one reference surface at leastonce per revolution of said spindle and passes a signal to a memorymeans each time a reference surface is detected; and, memory meansarranged to register the time interval between the signals received fromthe detector and to determine the unwinding velocity of said belt strap,said memory means activating said locking means when a preselected valueof the unwinding velocity is exceeded, thereby preventing furtherunwinding of said belt strap from said spindle.
 2. The arrangementaccording to claim 1, wherein said detector comprises an opto-electricaldetector, and wherein said at least one reference surface is lightreflective and surrounded by surfaces contrasting therewith.
 3. Thearrangement according to claim 2, wherein said reference surfaces areprovided on a substantially circular disc, which is concentric with saidspindle and co-rotates with the same, said reference surfaces comprisinga plurality of regularly spaced lines extending substantially radiallyon said disc.
 4. The arrangement according to claim 1, wherein saidreference surfaces are provided on a substantially circular disc, whichis concentric with said spindle and co-rotates with the same, saidreference surfaces comprising a plurality of regularly spaced linesextending substantially radially on said disc.
 5. The arrangement ofclaim 1 further comprising a second detector for sensing theacceleration/deceleration/inclination of said vehicle, said seconddetector comprising:a sphere; a substantially cup-shaped supportcontaining the sphere such that it is freely movable in every radialdirection from a positive of rest at a lowest part of the cup; atransmitter for generating signals and a receiver, one of which isarranged centrally above said lowest part of said cup, and the other ofwhich is arranged centrally below said lowest part, such that saidreceiver senses the signals from said transmitter when said sphereleaves said position of rest, and transmits said signals via a pulseforming circuit to an activating circuit, which activates said lockingmeans so as to prevent unwinding of said belt strap.
 6. A safety beltarrangement for protecting passengers in motor driven vehicles,comprising:at least one strap roller having a spindle mounted forrotation in a housing attached to the vehicle body; at least one beltstrap, one free end of which is attached to said spindle and which canbe wound onto and unwound from said spindle; biasing means urging saidspindle to rotate so as to keep said belt strap wound onto said spindle;locking means actuable for locking said spindle so as to prevent furtherunwinding of said belt strap; a plurality of spaced apart referencesurfaces provided on said belt strap; a detector which on unwinding ofsaid belt strap senses said reference surfaces and passes a signal to amemory means each time a reference surface is detected; and, memorymeans arranged to register the time interval between the signalsreceived from the detector and to determine the unwinding velocity ofsaid belt strap, said memory means activating said locking means when apreselected value of the unwinding velocity is exceeded, therebypreventing further unwinding of said belt strap from said spindle. 7.The arrangement according to claim 6, wherein said detector comprises anoptoelectrical detector, and wherein at least one reference surface islight reflective and surrounded by surfaces contrasting therewith. 8.The arrangement according to claim 7, wherein said reference surfacescomprise regularly spaced lines extending in the cross-direction of saidbelt strap.
 9. The arrangement according to claim 6, wherein saidreference surfaces comprise regularly spaced lines extending in thecross-direction of said belt strap.
 10. The arrangement of claim 6further comprising a second detector for sensing theacceleration/deceleration/inclination of said vehicle, said seconddetector comprising:a sphere; a substantially cup-shaped supportcontaining the sphere such that it is freely movable in every radialdirection from a position of rest at a lowest part of the cup; atransmitter for generating signals and a receiver, one of which isarranged centrally above said lowest part of said cup, and the other ofwhich is arranged centrally below said lowest part, such that saidreceiver senses the signals from said transmitter when said sphereleaves said position of rest, and transmits said signals via a pulseforming circuit to an activating circuit, which activates said lockingmeans so as to prevent unwinding of said belt strap.